Computer science notes
Topic 1
Topic 1.1.1
Identify the context for which a new system is planned.
A new system is planned to replace an old system that is:
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Inefficient
Redundant
Outdated
No longer suitable for its original purpose
A computer system includes:
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Hardware
Software
People working with it or using it
Updating a system may require:
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Training employees
Firing employees
Changing the server’s location
Some organizational issues include:
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Lack of attention to training
Lack of end user ownership of a system
Lack of stake holder and end user participation
Lack of guiding organizational and business strategies.
A feasibility report should be conducted and includes:
T – Technical feasibility
E – Economic feasibility
L – Legal feasibility
O – Operational feasibility
S – Schedule feasibility
Topic 1.1.2
Describe the need for change management.
Change management involves shifting the following from the present state to a desired state:
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individuals
teams
departments
organizations
The goal is to:
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Maximize benefits
Minimize negative impacts of change on individuals
Examples of negative impacts:
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Employees need proper training
Employees fear losing their jobs
Topic 1.1.3
Outline compatibility issues resulting from situations including legacy systems or business mergers
Legacy system: old technology, hardware, computer system or application program.
Reasons a legacy system may still be in use:
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Data cannot be converted to a newer format
Applications cannot be upgraded
Business merger: the combining of two or more business entities.
Businesses merge mainly to reduce costs.
The departments of both companies need to ensure that all subsystems are compatible.
The four strategies of integration are:
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Keep both information systems – high maintenance cost
Replace both information systems – High initial cost
Select best information systems from each company and combine them – difficult for employees
Select one company’s information system and drop the other – policy problems
Compatibility issues with business mergers:
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Language difference – Communication problems
Software incompatibility – The different software systems cannot operate satisfactorily,
cooperatively, independently or on the same computer
Topic 1.1.4
Compare the implementation of systems using a client’s hardware with hosting systems remotely.
SaaS (Hosted remotely) (Software as a service): A delivery software that allows data to be hosted and
managed on a remote data center.
SaaS benefits:
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Less expensive
Company only needs to adjust SaaS subscription monthly as required
Only web browser required to access SaaS applications
Wide range of devices support SaaS
Requires few IT personnel
Safe (Data is stored in cloud)
SaaS disadvantages:
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Possibility of data loss
Performance is low when compared to running on a local machine
SaaS integration is difficult
A locally hosted system is best for bigger company’s (Apple, Google, Amazon, etc.)
A remotely hosted system is best for smaller companies that don’t have the necessary equipment or
when the administration wants to outsource the responsibilities.
Topic 1.1.5
Evaluate alternative installation processes.
During the installation of a new system the old system will be retired and replaced with the new system.
The implementation(Changeover, conversion) methods are:
Parallel – Both systems work in parallel for a period of time.
Benefits:
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Limited risk
Outputs of both systems can be compared to ensure new system runs properly
If the new system fails, the company can return to the old system
The old system can be terminated when the company is satisfied with the new systems output
Drawbacks:
1) Extra costs and workload
2) Various organizational tasks
3) Not efficient
Big bang (direct, immediate) changeover – Immediately switch old system with new one.
Benefits:
1) Low initial cost
Drawbacks:
1) Extremely risky
2) All users need to be trained properly before the switch
Pilot – New system is introduced in one of the sites and is extended to other sites over time.
Benefits:
1) Low risk
2) Pilot site can serve as a model for other sites
Drawbacks:
1) None
Phased – One module of the system is converted at a time until the whole system is implemented.
Benefits:
Not much risk
Drawbacks:
Very time consuming
Training period is extended
Topic 1.1.6
Discuss problems that may arise as a part of data migration.
Data migration is the transfer of data between different formats, storage types and computer systems.
Problems that arise with data migration:
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Incapability of moving the information
Data may be lost or not transferred
Data can be misinterpreted
Topic 1.1.7
Suggest various types of testing.
The different types of testing are:
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Functional testing
Data testing
Alpha testing
Beta testing
Dry run testing
During unit testing
Integration testing
User acceptance testing
Debugging
Verification
Validation
Topic 1.1.8
Describe the importance of user documentation.
User documentation is a crucial part of a system as it is the document that explains the working of the
system to the user.
A well-made user documentation guides the user through using the system and thus increases
productivity. If the user documentation is simple, system implementation can happen faster because
users require less training to learn how to use the new system.
Users are non-technical people, they only need to know how to use the system. Therefore, the user
documentation does not involve detailed explanations of how the system works.
Topic 1.1.9
Evaluate different methods of providing user documentation.
The different methods of providing user documentation are:
Manuals:
Advantages:
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Can be provided online or offline
Potential use of multimedia features
Can be downloaded and printed
Can be read without using a PC or the internet
Disadvantages:
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Can be lost if printed
Sometimes limited to a booklet
Email support:
Advantages:
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Can be provided via email
Can resolve any problems by contacting the support team.
Disadvantages:
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Users need an internet connection
Users need to familiar with computers
Topic 1.1.10
Evaluate different methods of delivering user training.
The different methods of delivering user training:
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Self-instruction/study:
Users teach themselves in their own time with recourses that are provided.
Advantages:
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No tuition fees
User can study whenever they want
Disadvantages:
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No guidance
Final results depend on user motivation
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Formal classes:
Several students learning in the same class.
Advantages:
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Allows students to exchange ideas
Direct interaction with the expert
No technical communication barriers
Disadvantages:
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Disadvantages shy students
Obstruct a students learning ability by letting other students dominate the discussion.
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Online training:
Learning in an online classroom.
Advantages:
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Can be accessed from anywhere in the world
Very time efficient
Can be accessed at any time of day
Contributes to self-direction
Promotes critical thinking
Disadvantages:
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Need access to online learning environment
Some students may be excluded
Must have IT skills to function
Inappropriate for more dependent and immature learners because of high responsibility
Topic 1.1.11
Identify a range of causes of data loss
Data loss is when data is destroyed due to system failure, storage negligence or transmission or
processing errors.
Causes of data loss:
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Accidental deletion
Administrative errors
Data misplacement
Building fires
Closing the program without saving the file
Computer viruses
Continued use after signs of failure
Data corruption
Firmware corruption
Natural disasters
Outsiders deleting, stealing or altering information
Physical damage of the storage device
Power failure
Topic 1.1.12
Outline the consequences of data loss in a specified situation.
If a patient’s medical records are lost:
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life could be in danger.
Painful examination may have to be repeated.
Retrieval of the data may be time consuming
Retrieval may not always be possible.
Topic 1.1.13
Describe a range of methods that can be used to prevent data loss.
Methods which can be used to prevent data loss:
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Regular backing up of files
Firewall installations
Data storage in multiple locations
Removed hard copies
Anti-virus software
Human error reduction techniques
Online auto save backups
Redundancy:
Duplication of storage devices and data.
Removeable media:
Non-volatile storage devices used for fast backup and storage data that can store data permanently.
Failover system:
A computer system that switches to a spare system upon hardware failure. The secondary sever
becomes the primary server automatically.
Switchover system:
The primary and secondary servers interchange the primary role.
Topic 1.1.14
Describe strategies for managing releases and updates.
Strategies for managing releases:
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Patches – Fixing know bugs and vulnerabilities
Updates – Add new functionalities or fixing known bugs
Upgrades – Novel functionalities or characteristics and cumulative bug fixes
Releases – Final working versions of software applications
Topic 1.2.1
Define the terms: hardware, software, peripheral, network, human resources.
Hardware:
Physical components of a computer
Software:
Programs and data. A series of instructions that can be understood by a CPU
Peripheral:
Any auxiliary device that can work with a computer. Input/Output devices
Network:
Computer systems that are interconnected and share resources and data
Human resources:
People who are or could be used in an organization, business or economy
Topic 1.2.2
Describe the roles that a computer can take in a networked world.
The roles a computer can take in a networked world:
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Client – Receives data via the network
Server – Has saved data on it and offers it to other clients
E-mail server – Manages the flow of email in and out of the networks
Domain name system server – Attributes names to network addresses
Router – Accepts incoming quanta of information reads their destination and distributes them
Firewall - Controls data flow access among network entities
Topic 1.2.3
Discuss the social and ethical issues associated with a networked world.
The social and cultural issues with a networked world:
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Reliability – How well an IT system functions
Integrity – Protecting the completeness and accuracy of data
Inconsistency – duplicated data
Security – Protection of hardware, software and computer networks
Authenticity – Proving identity
Privacy – What extent data is used and disseminated to others
Anonymity – Conceal identity
Intellectual property – ideas, discoveries, photographs and films
Digital divide and equality of access – Inequal access
Surveillance – Using IT to monitor individuals
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Globalization and cultural diversity – IT help diminish importance boundaries
IT policies – Procedures and measures that promote appropriate use of computers and networks.
Standards and protocols – Rules and conventions that hardware developers follow
People and machines – interactions between IT and humans
Digital citizenship – Appropriate behavior in a digital world
Topic 1.2.4
Identify the relevant stakeholders when planning a new system.
Stakeholders:
Individuals, teams, groups or organizations that are interested in the realization of a project or may be
affected by the outcome of a project.
Relevant stakeholders:
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Frequent users of the system – Able to identify flaws and propose improvements.
Topic 1.2.5
Describe methods of obtaining requirements from stakeholders.
Methods of obtaining requirements from stakeholders:
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Interviewing stakeholders – Face to face procedures that obtains reliable data in the form of verbal
responses from a person or group
Questionnaires – Surveys that focus on taking samples from the population
Observation – Spending time in different departments and observing
Topic 1.2.6
Describe appropriate techniques for gathering the information needed to arrive at a workable solution.
Techniques for gathering information:
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Examining current systems – Examination of the current system and analysis of its functions and
procedures
Literature search – Identification, retrieval and management of various sources in order to find
information on a topic
Online databases – Search engines and information they provide
Competing products – Analysis of competitive factors their benefits and vulnerabilities
Topic 1.2.7
Construct suitable representations to illustrate system requirements.
The ways to illustrate system requirements:
System flow charts - Diagrams representing how different parts of the
system are linked together and how the system should work in general.
Data flow diagram - Diagram representing how data is moving through the
system.
Structure diagram - Diagrams representing the organization of a system,
usually with showing the different parts in hierarchical order.
Topic 1.2.8
Describe the purpose of prototypes to demonstrate the proposed system to the client.
A prototype:
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Attracts a client’s attention
Provides enough of the concept for the investors to decide if they want to fund the project
Encourages participation between users and developers
Gives an idea of the final product
Helps identify problems
Increases system development speed
Topic 1.2.9
Discuss the importance of iteration during the design process.
Iteration:
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Makes developers reconsider choices
Decides how the final product will look and function
Modifies the system
Improves the design
Makes sure everything works
Topic 1.2.10
Explain the possible consequences of failing to involve the end-user in the design process.
Consequences of failing to involve end users in the design process:
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Unlikely to be successful
Developed system may solve a different problem
Developed system may deal with issues outside of the projects scope
Topic 1.2.11
Discuss the social and ethical issues associated with the introduction of new IT systems.
Issues with the introduction of new IT systems:
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Machines replacing humans causing unemployment
Topic 1.2.12
Define the term usability.
Usability: The potential of a service, product or website to achieve user goals.
Topic 1.2.13
Identify a range of usability problems with commonly used digital devices.
GPS problems:
1. Small screen
2. Outdated street data
3. Inaccurate geographical data
Tablets:
1. Accidental touches
2. Small side buttons
3. Poorly written instructions
Game consoles:
1. Small screen
2. Short battery life
3. Buttons may be too small
PC’s:
1. Eyesight problems
2. Distracting reflections on screen
3. Difficult for left-handed people to use
Digital cameras:
1. Incorrect calibration of touch screen menus
2. Buttons are too small
3. Requires specific software to connect to a coputer
Phones:
1. Small keyboard
2. Some users may not need all of the features
MP3’s:
1. Small buttons
2. Fragile
3. Insufficient memory
Topic 1.2.14
Identify methods that can be used to improve the accessibility of systems.
Visual impairments:
Input:
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Braille input devices
Output:
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Speech output devices
Hearing and speech impairments:
Input:
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No problems
Output:
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Visual sound effects and subtitles
Cognitive problems and learning disabilities:
Input and output devices:
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Mobility impairments:
Identify a range of usability problems that can occur in a system.
Discuss the moral, ethical, social, economic and environmental implications of the interaction
between humans and machines.